As a conventional wheel that reduces road noise caused by air column resonance in a tire air chamber, a wheel in which a sub air chamber member that functions as a Helmholtz resonator is secured to an outer circumferential surface of a well portion in a tire air chamber, which one of the present inventors has already disclosed, is known (see, for example, FIGS. 2, 3, 9, etc. of Japanese Unexamined Patent Application Publication No. 2012-51397).
The wheel includes a first vertical wall surface, which is formed in a vertical wall provided to stand on an outer circumferential surface of a well portion so as to extend in a circumferential direction of the outer circumferential surface, and a second vertical wall surface, which is formed in one of rising portions of the well portion so as to extend in the circumferential direction and faces the first vertical wall surface in a width direction of the outer circumferential surface. A groove portion extending in the circumferential direction is formed on each of the first vertical wall surface and the second vertical wall surface, and the sub air chamber member is fitted between the first vertical wall surface and the second vertical wall surface.
The sub air chamber member includes a main body formed of resin and made up of a sub air chamber and a communication hole that allows the sub air chamber and the tire air chamber to communicate. The sub air chamber member further includes a first flange portion that is formed so as to extend from the main body toward the first vertical wall surface and extend in the circumferential direction and caught in the groove portion of the first vertical wall surface. The sub air chamber member further includes a second flange portion that is formed so as to extend from the main body toward the second vertical wall surface and extend in the circumferential direction and caught in the groove portion of the second vertical wall surface. The sub air chamber member is secured to the outer circumferential surface of the well portion by causing the first flange portion to be caught in the groove portion of the first vertical wall surface and causing the second flange portion to be caught in the groove portion of the second vertical wall surface. The cross section of the above-described sub air chamber member in the width direction is formed so as to have symmetry between left and right halves.
By the way, the radius or width of a wheel differs, depending on the size or form of a vehicle. Thus, when it is assumed to use a conventional wheel (see, for example, Japanese Unexamined Patent Application Publication No. 2012-51397) in a vehicle with a small wheel radius or width, the volume of a sub air chamber lessens as the wheel radius or width decreases.
However, when the volume of the sub air chamber lessens, the sub air chamber member decreases its silencing effect on an air column resonance sound in a tire air chamber and fails to sufficiently reduce road noise caused by the air column resonance sound in the tire air chamber.
Thus, the present application is aimed at providing a vehicle wheel that includes a sub air chamber member capable of ensuring a sufficient volume of a sub air chamber even when the wheel radius or width decreases.